Establishment Of Rat Functional Constipation Models By Selective Chemical Ablation Of The Enteric Plexus

Functional constipation is a common clinical chronic disease but etiology unknown,it can be divided into three types according to the patients' intestinal motility and anorectal function:colonic slow transit constipation(colonic dysmotility),outlet obstruction constipation and mixed.Studies in the European and American countries such as the United States and Spain have shown that the incidence of constipation is determined to be 6%-28%in the general population,approximately 50%of the patients were mixed constipation,combined colonic dysmotility and anorectal dysfunction.Causes and pathophysiology of mixed constipation were not entirely clear.At the same time,we lack an ideal animal model to simulate its pathophysiological processes.In this study,selective chemical ablation of the enteric plexus was used to establish slow transit constipation model and a mixed model combined slow transit constipation and outlet obstructed constipation.So we start to figure it out on two parts.PART 1 Establishment of rat slow transit constipation model by selective chemical ablation of the enteric plexusObjective:To establish an innovative rat model of slow transit constipation by selective chemical ablation of the colon enteric plexus.Methods:Sprague Dawley female rats,5-6 weeks old,were randomly divided into normal control group,sham operation group,treatment group ?,?,?,?.The normal control group without treatment,all animals in the sham operation group and treatment groups were accepted abdominal operation under anesthesia,the gauze containing 0.9%normal saline,0.05%,0.1%,0.25%,0.5%Benzalkonium chloride(BAC)was applied onto colon for 30 minutes.2 weeks after operation,food-intake,body weight,the number of feces,fecal dry weight in 24h and gastrointestinal transit time were recorded,then hematoxylin-eosin(HE)staining,immunohistochemistry,Elisa and Western Blot were used to evaluate the changes of colonic pathology,intestinal nerve cells,interstitial cells of Cajal,the concentration of neurotransmitters(5-HT)and apoptosis of intestinal cell.Results:Compared to the normal control group and sham operation group,the gastrointestinal transit time was significantly prolonged in the treatment group,and Benzalkonium chloride concentration was positively correlated.After HE and immunohistochemical staining,varying degrees of pathological changes were observed in the treatment groups and in line with the pathological changes of slow transit constipation,such as the reducing of intestinal nerve cells and the interstitial cells of Cajal,apoptosis increased and 5-HT concentrations were significantly reduced in treatment group III than other groups(P<0.01).Conclusion:The animal model of STC is successfully established by applying 0.25%BAC selective chemical ablation of the colon enteric plexus,the model making simple,stable and was more in line with pathological changes of slow transit constipation.PART 2 Establishment of rat models combined slow transit constipation and outlet obstructed constipation by selective chemical ablation of the enteric plexusObjective:To establish a rat model combined slow transit constipation and outlet obstructed constipation by selective chemical ablation of the colon and anorectal enteric plexus which is no reports previously.Methods:Sprague Dawley female rats were randomly divided into sham group,outlet obstruction group,slow transit group,and mixed constipation group.The sham and slow transit group were accepted abdominal operation under anesthesia,0.9%saline and 0.25%benzalkonium chloride were applied onto colon for 30 minutes,respectively;0.5%benzalkonium chloride was used on the anorectal of the outlet obstruction and mixed constipation group,then the mixed constipation group was given 0.25%benzalkonium chloride the same as the slow transit group.Two weeks after above operations,food-intake,body weight,fecal parameters,gastrointestinal transit time were recorded,then hematoxylin-eosin(HE)staining,immunohistochemistry,Elisa and Western Blot were used for the evaluation of colonic pathology.Results:The fecal dry weight decreased,colonic fecal retention and hirschsprung change were observed in the mixed constipation group,meanwhile the gastrointestinal transit time of was significantly prolonged.(P<0.05)The enteric plexus,Interstitial cells of Cajal,pheochromocyte and 5-HT concentrations were significantly decrease(P<0.05).Conclusions:The animal model combined slow transit constipation and outlet obstructed constipation was successfully established by applying benzalkonium chloride to chemical ablate of the enteric plexus.